Automatic wakeboarding in a pond

[Rick] sent in an awesome project he and his uncle [Charlie] have been working on for this summer. It’s a completely automatic wakeboarding system that tows [Charlie] and company from one end of his backyard pond and back again.

The entire system is supported by two towers at either end of the pond. Strung between these towers is a 420 foot cable that pulls the rider from one end to the other before stopping, and automatically continuing in the opposite direction. Apart from stopping and starting the motor attached to the cable, no user input is required. This means anyone lucky enough to make it to [Charlie]’s farm can wakeboard all afternoon without a break.

[Rick] posted a few short videos covering the internals of the system. From what we can see, the guys are using a LabJack U3-LV data acquisition unit to grab the speed, direction, and position of the rider. This data is sent to a laptop that controls the motor suspended on one of the towers.

There are a few more videos of this incredibly fun toy available after the break.

I really don’t see what’s so dangerous about this. I guess if are wakeboarding alone (dumb) and somehow get your head jammed into/wrapped around the cable (dumb) you might be in trouble. Do it with a friend sitting next to the kill switch and it’s no more dangerous (and in fact probably much safer) than getting towed behind a boat with a deadly arm chopper (ahem. propeller) attached to it (in a lake full of other arm chopping ski boats).

for reference, on a proper ski boat, the prop is under the boat on a straight shaft – either in a V or inline config with the engine. Normal runabout boats are more of the arm chopper variety when they have i/o (stern mount) outdrives. usually not an issue with a skier/wakeboarder/wakeskater, however it is damn near stupid to try and surf behind an I/O boat – we refer to people who try this on the lakes as our future chums.

This is great. You could probably start a business charging people for rides. The guy above me is just scared of the awesome sauce. You should probably have some one on the apply named “kill” switch but any one who doesn’t let go probably deserves the darwin award they are about to receive.

Did this back when I lived in Brunswick, GA. They used to have a place called ski rixen. You would get towed past alligators every now and then lol. It was on St. Simons Island I believe. It was 92 or 94. It seems like they are still in operation, although in FL now. http://www.skirixenusa.com/ It was a lot of fun (but expensive) so the builder should also have tons of fun but at a much better price :) At any rate it is always a challenge to secure things in water and good on the builder to get it all figured out :) Timely too, with the temps climbing!

neat someone did this in their own backyard – cable wakeboarding is actually quite common in europe (where the lakes don not allow normal gas boats), and actually down here in texas we have a cable park as well – http://www.texasskiranch.com. As for safety – even in the commercial cable parks, the handle never stops – think like a j-bar ski lift. you’d have to try pretty hard to get dragged by a tow handle, doubly so if unconscious.

I wasn’t able to find a picture but, there’s a setup like on a huge lake except in a big polygon in Bratislava at a public park. if you ever go there it’s at the end of the 2 and 4 tram lines through a camping ground.
never got a chance to go on it, but it looks fun.

Just so ya know, He does have a remote kill switch on his helmet now. But we’ve found that the best prevention against corpse towing is to hold the rope in your hands, and not tie it around your neck! :-)

The LabJack reads a quadrature encoder to track speed and distance. It also reads the buttons on the local and remote controls. It also provides a 0-5V speed reference to the motor controller.

The other USB box is an OnTrak Control Systems USB / relay/IO box. It just provides the motor controller with a direction indication.

Both devices provide DLLs for interfacing. The software I wrote allows on-the-fly adjustment of laps/speed, start/stop positions, lap distance, stop position(It can drop you off right on the beach), etc.

I use several languages and platforms at work. For this system, I used PowerBasic. It interfaced easily with the DLLs, has nice built-in communication libraries, and it’s nice and fast. The compiled program is about 75k.

If I were doing this on a production basis, I might use an embedded controller. But this is a one-off, So I used the systems and tools I had at hand and am comfortable with.